Spark plug



Apnl 17, 1392s.

l. 'HARRIS SPARK PLUG -Filed March 14 1924 /f //l f f f /////////J/ l fl l /gyaz Patented Apr. 17, 19.28.

UNITED STATES,

PATENT OFFICE.

SPARK PLUG'.

Application led Hatch 14, 1924. Serial No. 699,268.

This invention relates to improvements in spark plugs and has for anobject the provision of means to indicate whether or not the plug isproperly firing.

Another object of the invention is the provision of means forintensifying the spark within the engine cylinder and for preventingaccumulation of oil at the firing points, so that the points will notcarbonize l and so that properoperat-ion of the plug will be assured.

With the above and other objects in view, the invention further includesthe following novel features and details of construction,

.l to be hereinafter more fully described, illustrated in theaccompanying drawings and pointed out in the appended claim.

In the drawings Figure 1 is a sectional view of a spark plug constructedin accordance with the invention. l

Figurev 2 is a bottom plan view of the same.

Figure 3 is a sectional view on the line 3-3 of Figure 1.

Referring to the drawings in detail wherein like characters of referencedenote correspondingparts, the reference character 10 indicates the.shell of the plug which is exteriorly threaded as shown at 11 forremovable engagementfwith an engine in the usual manner. Located withinthe shell is a core 12 which is held therein by means of a nut or gland13, while suitable packing 14 is provided 'to prevent escape ofcompression through the plug.

The core 12 is of novel construction and includes an enlarged portion 15which is hollow so as tov provide a chamber 16, the

4o latter being provided with openings 17 and The core 12 carries a-sectional power electrode which includes sections 19 -and 20. The lastmentioned section is lthreaded at one end and passes through the opening18 and the wall of the latter is provlded with an annular groove 21which is adapted to receive a retaining element 22 which serves toconnect the section 20 of the electrode to the core. This retaininelement ma be of any suitable materia such as so t or moulten metalwhich is placed within the opening around the electrode section 2O so asto engage the threads and the groove 21 and after this metal becomeshardened the electrode section will be securely heldin place without anyauxiliary fastening means such as screws, nuts or the like. Theelectrode section extends beyond the top of the core and is providedwith a nut 23 for the retention of the usual lead wire. i

The section 19 of the power electrodeextends within the chamber 16 andis provided with a coil 24 which surrounds and is spaced from theadjacent end of the section 20 of the electrode. This provides a sparkgap or spark intensifier. It is preferred to form the core 12 and thechamber 16 of tough glass which will withstand a high temperature sothat the walls of the chamber will be transparent in order that it maybe seen whether or not the plug is functioning. The upper part of thechamber 16 forms a vacuum dome and as the openin 17 is of a restrictedcharacter and atmosp eric pressure is the same upon opposite sides ofthe opening, the passa e of water, gas fumes and so forth through theopening will be prevented.

The lower end of the shell 10 has extending 'therefrom a groundelectrode 25 which is provided with an upwardly and inwardly extendingarm 26 and a substantially circular terminal 27 which receives andsurrounds the adjacent end of the section 19 of the power electrode. Oilpumped into an engine cylinder and reaching the electrodes willtherefore gravitate down and drop from the arm 26, while the intensifiedspark at this end of the lug will keep the electrodes free from car onand in proper firing condition.

The invention is susceptible of various changes in its form, proportionsand minor details of construction and the right is herein reserved tomake such changes as properly fall within the scoperof the appendedclaim.

Having described the invention what is claimed 1s:

A spark plug comprising a. shell; an insulating core within the shell,said core be ing provided at one end with an enlarged head having aichamber therein, a sectional power electrode having one member thereofextending longitudinally through said insulatlng core and havin a 5 oneend thereof,` and chamber, the other member in alignment therewith andspiral formed at ocated within lsaid being supported having a portion.

thereof extendingv concentrically with the spiraly portion,"a groundelectrode secured to seid shell and having a loop portion sur- 10rounding said power electrode.-

In testimony7 whereof I affix my signature.`

ISAAC HARRIS.

